Objective: This study was undertaken to determine contemporary trends in the use of the Twin Block appliance among UK orthodontists, including the wear time currently prescribed. In addition, the study explored if there had been any change in wear time prescribed, considering recent research evidence proposing part-time wear. Design: Cross-sectional, online survey. Participants: Members of the British Orthodontic Society (BOS). Methods: The questionnaire was emailed to all BOS members in November 2021 and hosted on the QualtricsXM platform. The questionnaire was piloted for content validity and tested for reliability. Results: A response rate of 19% was attained. Nearly all (n = 244, 99%) participants used the Twin Block, and 90% (n = 218) prescribed full-time wear including/excluding eating. Although the majority (n = 168, 69%) had not made changes to their wear time prescriptions, nearly one-third (n = 75, 31%) had. Those who reported a change in their prescriptions currently prescribe less wear time than before, and commonly quoted ‘research evidence’ as the reason. A wide range in success rates (41%–100%) was reported, with patient compliance as the main reason for treatment discontinuation. Conclusion: The Twin Block is a popular functional appliance among orthodontists in the UK, originally designed by Clark to be worn full time to maximise functional forces applied to the dentition. However, this wear regime may place considerable strain on patient compliance. Most participants prescribed full-time Twin Block wear excluding eating. Approximately one-third of orthodontists made changes to their wear time prescriptions during their practising career, and currently instruct less wear time than before.

Introduction With an increasing demand to improve patient safety within the NHS, it is important to ensure that measures are undertaken to continually improve patient care. Wrong site surgery has been defined as a 'never event'. This article highlights the importance of preventing wrong tooth extraction within orthodontics through an audit spiral over five years investigating the accuracy and clarity of orthodontic extraction letters at the University Dental Hospital of Manchester.Aims To examine compliance with the standards for accuracy and clarity of extraction letters and the incidence of wrong tooth extractions, and to increase awareness of the errors that can occur with extraction letters and of the current guidelines.Method A retrospective audit was conducted examining extraction letters sent to clinicians outside the department.Results It can be seen there has been no occurrence of a wrong site tooth extraction. The initial audit highlighted issues in conformity, with it falling below expected standards. Cycle two generally demonstrated a further reduction in compliance. Cycle three appeared to result in an increase in levels of compliance. Cycles 4 and 5 have demonstrated gradual improvements. However, it is noteworthy that in all cycles the audit standards were still not achieved, with the exception of no incidences of the incorrect tooth being extracted.Conclusion This audit spiral demonstrates the importance of long term re-audit to aim to achieve excellence in clinical care. There has been a gradual increase in standards through each audit.

The final part of this four part series will review the effects of orthodontic treatment with endodontically treated teeth. There are few published articles on the challenges faced when treatment planning cases with the integration of both endodontics and orthodontics. This article will aim to summarize the implications of endodontic treatment on orthodontic tooth movement using current evidence, followed by some case examples highlighting aspects of the orthodontic-endodontic interface. CPD/Clinical Relevance: With an increase in the number of patients undergoing orthodontic treatment, there is a greater need for clinicians to be aware of the orthodontic management of endodontically treated teeth and also managing endodontic complications during orthodontic treatment.